Friday, October 10, 2008

Shark Virgin Birth

A female Atlantic blacktip shark named Tidbit has produced a pup without the presence or aid of a male shark. Scientists have confirmed only the second-known instance of “virgin birth” in a shark using DNA testing.

Beth Firchau, the Curator of Fishes at the Virginia Aquarium & Marine Science Center, in Virginia Beach confirmed that Tidbit came to them shortly after being born in the wild and has lived there for the past 8 years without the presence of a male shark.

The 5’ (1.5 m) Tidbit passed on after being removed from her tank for a routine veterinary exam. The necropsy to discover the cause of death revealed that Tidbit was carrying a fully-developed pup nearly ready to be born. This fact was confirmed by Beth Firchau.

The scientists were quick to caution that these rare asexual births should not be viewed as a means to prop up the declining shark populations.

Demian Chapman, a shark scientist with the Institute for Ocean Conservation Science at Stony Brook University in New York state, performed DNA testing that showed the pup had no father. Virgin birth such as this is known as parthenogenesis.

It was Chapman who proved that a hammerhead shark born at a zoo in Omaha in 2002 was also the result of parthenogenesis. Normally some shark species can have up litters of up to a dozen or more pups; but, the two parthenogenesis pregnancies produced just one pup each.

"It tells us that the original case we documented last year was not some fluke of nature. This is something that might be more common than we think it is, and widespread among sharks," Chapman said in a telephone interview.

“Parthenogenesis also has been documented in Komodo dragons, snakes, birds, fish and amphibians,” Chapman said.

"It's a finding that kind of rewrites the textbooks a little," Chapman said. "It just goes to show how the ocean keeps its secrets very well. And the sharks in particular."

"Of course, sharks are being killed at such a rate that unless we do something to stop that, we're not even going to learn all their secrets before they're gone," Chapman added.

1 comment:

kathi said...

Great stuff today, P!

I'm going to have to look up this virgin birth stuff. Do you think that means that there is a chance that the eggs Sophie lays could hatch? She's never been near a male 'too.

Have a great day!